// if (this.fetch) {
//     return
// }

let this_ = window;
let support = {
    searchParams: 'URLSearchParams' in this_,
    iterable: 'Symbol' in this_ && 'iterator' in Symbol,
    blob: 'FileReader' in this_ && 'Blob' in this_ && (function () {
        try {
            new Blob()
            return true
        } catch (e) {
            return false
        }
    })(),
    formData: 'FormData' in this_,
    arrayBuffer: 'ArrayBuffer' in this_
}

if (support.arrayBuffer) {
    let viewClasses = [
        '[object Int8Array]',
        '[object Uint8Array]',
        '[object Uint8ClampedArray]',
        '[object Int16Array]',
        '[object Uint16Array]',
        '[object Int32Array]',
        '[object Uint32Array]',
        '[object Float32Array]',
        '[object Float64Array]'
    ]

    var isDataView = function (obj) {
        return obj && DataView.prototype.isPrototypeOf(obj)
    }

    var isArrayBufferView = ArrayBuffer.isView || function (obj) {
        return obj && viewClasses.indexOf(Object.prototype.toString.call(obj)) > -1
    }
}

function normalizeName(name) {
    if (typeof name !== 'string') {
        name = String(name)
    }
    if (/[^a-z0-9\-#$%&'*+.^_`|~]/i.test(name)) {
        throw new TypeError('Invalid character in header field name')
    }
    return name.toLowerCase()
}

function normalizeValue(value) {
    if (typeof value !== 'string') {
        value = String(value)
    }
    return value
}

// Build a destructive iterator for the value list
function iteratorFor(items) {
    let iterator = {
        next: function () {
            let value = items.shift()
            return {done: value === undefined, value: value}
        }
    }

    if (support.iterable) {
        iterator[Symbol.iterator] = function () {
            return iterator
        }
    }

    return iterator
}


function Headers(headers) {
    this.map = {}

    if (headers instanceof Headers) {
        headers.forEach(function (value, name) {
            this.append(name, value)
        }, this)
    } else if (Array.isArray(headers)) {
        headers.forEach(function (header) {
            this.append(header[0], header[1])
        }, this)
    } else if (headers) {
        Object.getOwnPropertyNames(headers).forEach(function (name) {
            this.append(name, headers[name])
        }, this)
    }
}

Headers.prototype.append = function (name, value) {
    name = normalizeName(name)
    value = normalizeValue(value)
    let oldValue = this.map[name]
    this.map[name] = oldValue ? oldValue + ',' + value : value
}

Headers.prototype['delete'] = function (name) {
    delete this.map[normalizeName(name)]
}

Headers.prototype.get = function (name) {
    name = normalizeName(name)
    return this.has(name) ? this.map[name] : null
}

Headers.prototype.has = function (name) {
    return this.map.hasOwnProperty(normalizeName(name))
}

Headers.prototype.set = function (name, value) {
    this.map[normalizeName(name)] = normalizeValue(value)
}

Headers.prototype.forEach = function (callback, thisArg) {
    for (let name in this.map) {
        if (this.map.hasOwnProperty(name)) {
            callback.call(thisArg, this.map[name], name, this)
        }
    }
}

Headers.prototype.keys = function () {
    let items = []
    this.forEach(function (value, name) {
        items.push(name)
    })
    return iteratorFor(items)
}

Headers.prototype.values = function () {
    let items = []
    this.forEach(function (value) {
        items.push(value)
    })
    return iteratorFor(items)
}

Headers.prototype.entries = function () {
    let items = []
    this.forEach(function (value, name) {
        items.push([name, value])
    })
    return iteratorFor(items)
}

if (support.iterable) {
    Headers.prototype[Symbol.iterator] = Headers.prototype.entries
}

function consumed(body) {
    if (body.bodyUsed) {
        return Promise.reject(new TypeError('Already read'))
    }
    body.bodyUsed = true
}


function fileReaderReady(reader) {
    return new Promise(function (resolve, reject) {
        reader.onload = function () {
            resolve(reader.result)
        }
        reader.onerror = function () {
            reject(reader.error)
        }
    })
}

function readBlobAsArrayBuffer(blob) {
    let reader = new FileReader()
    let promise = fileReaderReady(reader)
    reader.readAsArrayBuffer(blob)
    return promise
}

function readBlobAsText(blob) {
    let reader = new FileReader()
    let promise = fileReaderReady(reader)
    reader.readAsText(blob)
    return promise
}

function readArrayBufferAsText(buf) {
    let view = new Uint8Array(buf)
    let chars = new Array(view.length)

    for (let i = 0; i < view.length; i++) {
        chars[i] = String.fromCharCode(view[i])
    }
    return chars.join('')
}

function bufferClone(buf) {
    if (buf.slice) {
        return buf.slice(0)
    } else {
        let view = new Uint8Array(buf.byteLength)
        view.set(new Uint8Array(buf))
        return view.buffer
    }
}

function Body() {
    this.bodyUsed = false

    this._initBody = function (body) {
        this._bodyInit = body
        if (!body) {
            this._bodyText = ''
        } else if (typeof body === 'string') {
            this._bodyText = body
        } else if (support.blob && Blob.prototype.isPrototypeOf(body)) {
            this._bodyBlob = body
        } else if (support.formData && FormData.prototype.isPrototypeOf(body)) {
            this._bodyFormData = body
        } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
            this._bodyText = body.toString()
        } else if (support.arrayBuffer && support.blob && isDataView(body)) {
            this._bodyArrayBuffer = bufferClone(body.buffer)
            // IE 10-11 can't handle a DataView body.
            this._bodyInit = new Blob([this._bodyArrayBuffer])
        } else if (support.arrayBuffer && (ArrayBuffer.prototype.isPrototypeOf(body) || isArrayBufferView(body))) {
            this._bodyArrayBuffer = bufferClone(body)
        } else {
            throw new Error('unsupported BodyInit type')
        }

        if (!this.headers.get('content-type')) {
            if (typeof body === 'string') {
                this.headers.set('content-type', 'text/plain;charset=UTF-8')
            } else if (this._bodyBlob && this._bodyBlob.type) {
                this.headers.set('content-type', this._bodyBlob.type)
            } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
                this.headers.set('content-type', 'application/x-www-form-urlencoded;charset=UTF-8')
            }
        }
    }

    if (support.blob) {
        this.blob = function () {
            let rejected = consumed(this)
            if (rejected) {
                return rejected
            }

            if (this._bodyBlob) {
                return Promise.resolve(this._bodyBlob)
            } else if (this._bodyArrayBuffer) {
                return Promise.resolve(new Blob([this._bodyArrayBuffer]))
            } else if (this._bodyFormData) {
                throw new Error('could not read FormData body as blob')
            } else {
                return Promise.resolve(new Blob([this._bodyText]))
            }
        }

        this.arrayBuffer = function () {
            if (this._bodyArrayBuffer) {
                return consumed(this) || Promise.resolve(this._bodyArrayBuffer)
            } else {
                return this.blob().then(readBlobAsArrayBuffer)
            }
        }
    }

    this.text = function () {
        let rejected = consumed(this)
        if (rejected) {
            return rejected
        }

        if (this._bodyBlob) {
            return readBlobAsText(this._bodyBlob)
        } else if (this._bodyArrayBuffer) {
            return Promise.resolve(readArrayBufferAsText(this._bodyArrayBuffer))
        } else if (this._bodyFormData) {
            throw new Error('could not read FormData body as text')
        } else {
            return Promise.resolve(this._bodyText)
        }
    }

    if (support.formData) {
        this.formData = function () {
            return this.text().then(decode)
        }
    }

    this.json = function () {
        return this.text().then(JSON.parse)
    }

    return this
}

// HTTP methods whose capitalization should be normalized
let methods = ['DELETE', 'GET', 'HEAD', 'OPTIONS', 'POST', 'PUT']

function normalizeMethod(method) {
    let upcased = method.toUpperCase()
    return (methods.indexOf(upcased) > -1) ? upcased : method
}


function Request(input, options) {
    options = options || {}
    let body = options.body

    if (input instanceof Request) {
        if (input.bodyUsed) {
            throw new TypeError('Already read')
        }
        this.url = input.url
        this.credentials = input.credentials
        if (!options.headers) {
            this.headers = new Headers(input.headers)
        }
        this.method = input.method
        this.mode = input.mode
        if (!body && input._bodyInit != null) {
            body = input._bodyInit
            input.bodyUsed = true
        }
    } else {
        this.url = String(input)
    }

    this.credentials = options.credentials || this.credentials || 'omit'
    if (options.headers || !this.headers) {
        this.headers = new Headers(options.headers)
    }
    this.method = normalizeMethod(options.method || this.method || 'GET')
    this.mode = options.mode || this.mode || null
    this.referrer = null

    if ((this.method === 'GET' || this.method === 'HEAD') && body) {
        throw new TypeError('Body not allowed for GET or HEAD requests')
    }
    this._initBody(body)
}

Request.prototype.clone = function () {
    return new Request(this, {body: this._bodyInit})
}

function decode(body) {
    let form = new FormData()
    body.trim().split('&').forEach(function (bytes) {
        if (bytes) {
            let split = bytes.split('=')
            let name = split.shift().replace(/\+/g, ' ')
            let value = split.join('=').replace(/\+/g, ' ')
            form.append(decodeURIComponent(name), decodeURIComponent(value))
        }
    })
    return form
}

function parseHeaders(rawHeaders) {
    let headers = new Headers()
    rawHeaders.split(/\r?\n/).forEach(function (line) {
        let parts = line.split(':')
        let key = parts.shift().trim()
        if (key) {
            let value = parts.join(':').trim()
            headers.append(key, value)
        }
    })
    return headers
}

Body.call(Request.prototype)

function Response(bodyInit, options) {
    if (!options) {
        options = {}
    }

    this.type = 'default'
    this.status = 'status' in options ? options.status : 200
    this.ok = this.status >= 200 && this.status < 300
    this.statusText = 'statusText' in options ? options.statusText : 'OK'
    this.headers = new Headers(options.headers)
    this.url = options.url || ''
    this._initBody(bodyInit)
}

Body.call(Response.prototype)

Response.prototype.clone = function () {
    return new Response(this._bodyInit, {
        status: this.status,
        statusText: this.statusText,
        headers: new Headers(this.headers),
        url: this.url
    })
}

Response.error = function () {
    let response = new Response(null, {status: 0, statusText: ''})
    response.type = 'error'
    return response
}

let redirectStatuses = [301, 302, 303, 307, 308]

Response.redirect = function (url, status) {
    if (redirectStatuses.indexOf(status) === -1) {
        throw new RangeError('Invalid status code')
    }

    return new Response(null, {status: status, headers: {location: url}})
}

let _xhrs = []

function remove(xhr) {
    if (xhr.tag !== undefined) {
        let i = _xhrs.indexOf(xhr)
        /* istanbul ignore else  */
        if (i !== -1) {
            _xhrs.splice(i, 1)
        }
    }
}


module.exports = function (input, init,tag) {
    return new Promise(function (resolve, reject) {
        let request = new Request(input, init);
        let xhr = new XMLHttpRequest();

        if (tag !== undefined) {
            xhr.tag = tag
            _xhrs.push(xhr)
        }

        xhr.onload = function () {
            //401token验证失败
            if(xhr.status === 401){
                reject({status:xhr.status,msg:xhr.statusText?xhr.statusText:'token验证失败'});
                return;
            }
            if(xhr.status !== 200){
                reject({status:xhr.status,msg:xhr.statusText?xhr.statusText:'网络出错'});
                return;
            }
            let options = {
                status: xhr.status,
                statusText: xhr.statusText,
                headers: parseHeaders(xhr.getAllResponseHeaders() || '')
            }
            options.url = 'responseURL' in xhr ? xhr.responseURL : options.headers.get('X-Request-URL')
            let body = 'response' in xhr ? xhr.response : xhr.responseText;
            remove(xhr);
            resolve(new Response(body, options))
        }

        xhr.onerror = function () {
            remove(xhr);
            reject({status:xhr.status,msg:xhr.statusText?xhr.statusText:'网络出错'});
        }

        //不执行超时
        // xhr.ontimeout = function () {
        //     reject({status:xhr.status,msg:xhr.statusText?xhr.statusText:'网络超时'});
        // }

        xhr.open(request.method, request.url, true)

        if (request.credentials === 'include') {
            xhr.withCredentials = true;
        } else if (request.credentials === 'omit') {
            xhr.withCredentials = false;
        }

        if ('responseType' in xhr && support.blob) {
            xhr.responseType = 'blob'
        }

        request.headers.forEach(function (value, name) {
            xhr.setRequestHeader(name, value)
        });

        xhr.send(typeof request._bodyInit === 'undefined' ? null : request._bodyInit)
    })
};

module.exports.abort = function(tag) {
    for (let i = _xhrs.length - 1; i > -1; i--) {
        let xhr = _xhrs[i];
        if (xhr.tag === tag) {
            _xhrs.splice(i, 1);
            xhr.abort();
        }
    }
};